Password complexity in ESXi and how to change

1. Log in to the ESXi Shell and acquire root privileges.

2. Open the passwd file with a text editor.
For example, vi /etc/pam.d/passwd

3. Edit the following line.
password requisite /lib/security/$ISA/pam_passwdqc.so retry=N min=N0,N1,N2,N3,N4

4. Save the file.

For example:
when you open the fie edit the following entries:

password requisite /lib/security/$ISA/pam_passwdqc.so retry=2 min=13,10,6,5,7


With this setting in effect, the password requirements are:
-retry=2: A user is allowed 3 attempts to enter a sufficient password.
-N0=13: Passwords containing characters from one character class must be at least 12 characters long.
-N1=10: Passwords containing characters from two character classes must be at least nine characters long.
-N2=6: Pass phrases must contain words that are each at least eight characters long.
-N3=5: Passwords containing characters from three character classes must be at least seven characters long.
-N4=7: Passwords containing characters from all four character classes must be at least six characters long.

https://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vsphere.security.doc_50%2FGUID-F48903DA-8A66-47C7-9796-CD12339B2164.html